ASP.NET Core Web API Interview Question #23

Why should API endpoints avoid exposing EF Core entities directly?

Web API & REST Fundamentals, Controllers, HTTP Methods & Status Codes Junior Beginner

Quick Interview Answer

Persistence entities are designed around database and domain concerns, while API contracts are designed for clients. Returning entities directly can expose internal fields, create serialization problems with navigation properties, encourage overposting, and tightly couple the API to the database model.

Detailed Explanation

Mapping entities to response DTOs and request DTOs creates a deliberate boundary between storage and the external API.

Code Example

var response = new ProductResponse
{
    Id = product.Id,
    Name = product.Name,
    Price = product.Price
};

return Ok(response);